In various factories and experimental facilities, when data sampled by a waveform measurement device and so forth are subjected to waveform display in there is a case where waveform comparison is needed between periodically changed waveforms in at not less than two specified ranges. For example, there are cases of comparison of waveform data of periodic voltage obtained by an oscilloscope, and so forth, daily comparison of yields of production in a chemical plant using a trend graph, comparison between quantity of production at daytime shift and that at night shift in a rotating shift system in a factory using the trend graph, and so forth. Although a method of comparing not less than two waveforms is, for example, illustrated in a patent document 1 set forth hereunder, the waveforms to be compared are limited to a present waveform and a past waveform, so that waveforms at not less than two arbitrary time zones can not be compared with each other. In the past, when the waveforms in at not less than two arbitrary specified ranges are compared, the respective waveforms are allowed to be displayed on two display windows, and two display windows are arranged one above the other, thereby executing comparison of two waveforms.
A waveform display device for executing waveform display of waveforms in at not less than two specified ranges is now described with reference to FIG. 6. In FIG. 6, waveform data obtained by a measurement device of an oscilloscope and so forth (not shown) is stored in a storage section 101. An input section 102 is a mouse, keyboard and so forth and executes input. A display section 103 is a monitor and so forth and executes waveform display and so forth. A control section 104 is connected to the storage section 101, input section 102, display section 103 and has waveform display means 105. The waveform display means 105 executes waveform display of waveform data stored in the storage section 101 on the display section 103 by the input of the input section 102.
Operations of the waveform display device shown in FIG. 6 are now described hereunder. FIG. 7 is a sample of display of waveform data stored in the storage section 101. A waveform serving as a standard of comparison at a time zone between 8:00 of the 29th to 0:00 of the next day is displayed on a waveform window 111. A waveform at a time zone between 8:00 of the 30th to 0:00 of the next day is displayed on a waveform window 112.
Waveform data are obtained by a measurement device such as an oscilloscope and so forth and are stored in the storage section 101. A user operates the control section 104 by the input section 102, and reads out the waveform data stored in the storage section 101, and displays the display windows 111, 112 side-by-side on the display section 103. Comparison of the waveform data is executed by displaying the display windows 111, 112 side-by-side on the display section 103.
[Patent Document] JP 2008-70295A
Although it is possible to compare waveforms in arbitrary ranges, since the waveforms are displayed by use of a plurality of display windows, as the number of ranges of the waveforms to be compared is increased, the waveform area of one display window is narrower, causing a problem that the waveforms are difficult to be seen.